1. Field of the Invention
The present invention relates to a method of preventing failure of reading wireless tags, and a wireless tag data management system.
2. Description of the Related Art
Radio frequency identification (RFID) systems are well known as technology that identifies data about products during manufacture and commercial transactions. Most RFID systems include wireless tags, a wireless tag reader/writer, and a host computer. Each wireless tag has a tiny wireless chip (integrated circuit). The wireless tag reader/writer can receive electric waves transmitted from any wireless tag, in non-contact fashion, to acquire the tag data containing the tag ID. The host computer obtains the tag data from the wireless tag reader/writer and processes the tag data. Thus, the tag data, which is data about the product to which the wireless tag is attached, can be read by using the wireless tag reader/writer in non-contact fashion. The tag data can be sent via the driver incorporated in the host computer and be utilized in various applications. This is why the RFID system is used in various business fields.
However, the wireless tag is detected only by reading the data from it. Hence, if the wireless tag reader/writer fails to read the tag data, whether the product has no wireless tags or the tag data cannot be read from the wireless tag cannot be determined at all.
In order to prevent such failure of reading the tag data, a technique has been developed (see, for example, Jpn. Pat. Appln. Laid-Open Publication No. 2006-209761). This technique resides in attaching a wireless tag (parent tag) to the product, in addition to the wireless tag (child tag) identifying the product. The parent tag is used for group management of products. That is, the parent tag holds the group ID of the product, making it possible to identify the group to which the product belongs.
However, the technique described above is disadvantageous because the parent tag must be used to achieve group management of products in addition to the child tag. Further, both the parent tag and the child tag must hold data that represents the parent-child relationship. In view of this, the parent tag can hardly be attached to the product in practice.